On receiving the 1945 Nobel Prize in Medicine for discovering penicillin, Alexander Fleming finished his lecture with a warning: ‘There is the danger,’ he said, ‘that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant.’ Antibiotic resistance is now one of the biggest threats to global health, food security and development. It could kill as many as 10 million people a year by 2050.

According to the World Health Organisation’s 2017 Global Tuberculosis Report, there were almost half a million cases of multiple-drug resistant TB in 2016 – cases that are resistant to the two most powerful drugs. Only one in five patients were started on treatment and only half of them were cured.

Antibiotics are routinely given to patients undergoing common surgical procedures (including caesarean sections and hip replacements) to prevent them from getting infections during and after surgery. But rising resistance to the drugs normally doled out before operations is threatening the safety of such procedures. A 2015 Lancet study found that in the United States, 39 per cent of surgical site infections after caesareans are caused by organisms that are resistant to the standard antibiotics given to the patient before the procedure.

Such common infections as gonorrhoea, pneumonia and TB, once easily treated with penicillin, are becoming increasingly difficult to cure. That means more reliance on last-line antibiotics. But sometimes even last-line drugs don’t work and we simply run out of options. John Turnidge, an Australian expert on gonorrhoea antibiotic resistance, told me that the country was considering going back back to an old drug called spectinomycin, which has some toxicity. ‘Everything else is experimental,’ he told me.

Colistin, discovered in Japan in 1949, was one of the first antibiotics to be effective against gram-negative bacteria such as Pseudomonas aeruginosa which can cause pneumonia and surgical site infections. It went out of fashion for human use in the 1970s because of its high toxicity and associated kidney problems. But it has made a comeback in recent years and is now used as a last resort therapy for multiple-drug resistant gram-negative bacteria.

British and Chinese scientists have recently reported, however, that the colistin-resistance gene MCR-1, first identified in E. coli in Chinese pigs in 2015, has since been discovered in farm animals and people in more than thirty countries across five continents. The findings ‘pose a significant public health threat’.

Research into new antibiotics isn’t a priority for the pharmaceutical industry; it’s a lot less lucrative than cancer therapies, for example. But it does go on, and earlier this year scientists in Italy discovered a new antibiotic that is highly effective against bacteria resistant to known antimicrobials. Pseudouridimycin, found in soil collected from under a cypress tree in Tuscany, appears to combat infections in mice.

Clinical trials will probably start in the next three years; it will be some time before it’s available on the market. It’s also likely to be far more expensive than the drugs we have today, raising questions about who will have access to new antibiotics in the future. In any case, a new antibiotic is only ever a temporary fix, because bacteria will eventually develop resistance – sooner rather than later if current practices continue.

As Ramanan Laxminarayan, the director of the Center for Disease Dynamics, Economics and Policy in New Delhi, recently told me, ‘the current problem really is the fact that people don’t take it into account that their overuse is hurting everyone else’ – it’s a tragedy of the commons. ‘Some people not doing the right thing in respect to antibiotics is drawing away from the global stock of effectiveness,’ Laxminarayan said.

The answer isn’t to restrict access to the drugs, but to ensure they are used responsibly. Doctors who prescribe unnecessary antibiotics, pharmacists who dispense them, and patients who demand them, all bear some responsibility for the rise in antimicrobial resistance. But the burden doesn’t only fall on individuals: it’s also a matter for health services, the pharmaceutical, agricultural and food industries, and the governments that regulate them.